The Buy Odds Converter takes exchange-side buy odds and the market spread, infers the tick size from the spread precision, and converts them into the true outcome odds a user would expect to see on a bookmaker.
The buy odds converter turns the buy odds on an exchange or prediction-market order book into the odds of the outcome itself, the way a bookmaker would show them, allowing for the spread. Enter the buy odds and the spread to get the converted odds.
Converted odds = buy odds ÷ (buy odds × (1 + spread) − 1)
Converted implied probability = 1 + spread − 1 ÷ buy oddsThe tick size, the smallest step a price can move, is read from the spread's decimal places: 0.01 gives a 0.01 tick and 0.005 gives a 0.001 tick. The result is rounded to that precision.
| Buy odds | Spread | Converted odds |
|---|---|---|
| 2.00 | 0.01 | 1.96 |
| 3.00 | 0.01 | 1.48 |
| 1.50 | 0.02 | 2.83 |
Exchange buy prices are quoted differently from bookmaker odds, so the raw number isn't directly comparable. Converting it gives the odds a bookmaker would show for the same position, so you can compare prices across both.
The spread is the gap between the buy and sell prices. The converter adds it to the implied probability, so a wider spread gives lower converted odds for the same buy odds.